P3-1 Spatial Sound Localization Model Using Neural Network—Rodolfo Venegas, Marcelo Lara, Universidad Tecnológica de Chile - Santiago, Chile; Rafael Correa, Universidad Tecnológica Metropolitana - Santiago, Chile; Sergio Floody, Universidad Tecnológica de Chile - Santiago, ChileThis paper presents the design, implementation, and training of a spatial sound localization model for broadband sound in an anechoic environment inspired in the human auditory system and implemented using artificial neural networks. The data acquisition was made experimentally. The model consists in a nonlinear transformer that possesses one module of ITD, ILD, and ISLD extraction and a second module constituted by a neural network that estimates the sound source position in elevation and azimuth angle. A comparative study of the model performances using three different bank filters and a sensitivity analysis of the neural network inputs are also presented. The average error is 2.3º. This work was supported by the FONDEI fund of Universidad Tecnológica de Chile.

P3-2 Aurally Motivated Analysis for Scattered Sound in Auditoria—Molly K. Norris, Rensselaer Polytechnic Institute - Troy, NY, USA, Kirkegaard Associates, Chicago, IL, USA; Ning Xiang, Ana M. Jaramillo, Rensselaer Polytechnic Institute - Troy, NY, USAThe goal of the first part of this work was to implement an aurally-adequate time-frequency analysis technique as a motivated first effort that takes into account binaural hearing with the implementation goal of the analysis of sound scattering data. The second part of this work aimed to use the developed model in the analysis of different scattering surfaces implemented in a room acoustics modeling program. This was an attempt to start to gain an understanding of what kind of visual changes could be expected when one alters the coefficients used to model scattering in conjunction with the Lambert scattering model. This paper is the pursuit of a method for visually representing scattering effects that directly correlates with human perception.

P3-3 Audibility of Spectral Differences in Head-Related Transfer Functions—Pablo Faundez Hoffmann, Henrik Møller, Aalborg University - Aalborg, DenmarkThe spatial resolution at which head-related transfer functions (HRTFs) are available is an important aspect in the implementation of three-dimensional sound. Specifically, synthesis of moving sound requires that HRTFs are sufficiently close so the simulated sound is perceived as moving smoothly. How close they must be, depends directly on how much the characteristics of neighboring HRTFs differ, and, most important, when these differences become audible. Differences between HRTFs exist in the interaural delay (ITD) and in the spectral characteristics, i.e., the magnitude spectrum of the HRTFs. The present study investigates the audibility of the spectral characteristics. To this purpose, binaural audibility thresholds of differences between minimum-phase representations of HRTFs are measured and evaluated.

P3-4 Looking for a Relevant Similarity Criterion for HRTF Clustering: A Comparative Study—Rozenn Nicol, Vincent Lemaire, Alexis Bondu, Sylvain Busson, France Telecom R&D - Lannion, FranceFor high-fidelity Virtual Auditory Space (VAS), binaural synthesis requires individualized head-related transfer functions (HRTF). An alternative to exhaustive measurement of HRTF consists in measuring a set of representative HRTF in a few directions. These selected HRTF are considered as representative because they summarize all the necessary spatial and individual information. The goal is to deduce the HRTF in nonmeasured directions from the measured ones by appropriate modeling. Clustering is applied in order to identify the representative directions, but the first issue relies on the definition of a relevant distance criterion. This paper presents a comparative study of several criteria taken from literature. A new insight in HRTF (dis)similarity is proposed.

P3-5 Evaluation of a 3-D Audio System with Head Tracking—Jan Abildgaard Pedersen, Pauli Minnaar, AM3D A/S - Aalborg, DenmarkA 3-D audio system was evaluated in an experiment where listeners had to “shoot down” real and virtual sound sources appearing from different directions around them. The 3-D audio was presented through headphones, and head tracking was used. In order to investigate the influence of head movements both long and short stimuli were used. Twenty six people participated, of which half were students and half were pilots. The results were analyzed by calculating a localization offset and a localization uncertainty. For azimuth no significant offset was found, whereas for elevation an offset was found that is strongly correlated with the stimulus elevation. The uncertainty for real and virtual sound sources was 10 degrees and 14 degrees in azimuth and 12 degrees and 24 degrees in elevation.

P3-7 Visualization of Perceptual Parameters in Interactive User Interfaces: Application to the Control of Sound Spatialization—Olivier Delerue, IRCAM - Paris, FranceThis paper addresses the general problem of designing graphical user interfaces for nonexpert users. The key idea is to help the user anticipating his actions by displaying, in the interaction area, the expected evolution of a quality criterion according to the degrees of freedom that are being monitored. This concept is first applied to the control of sound spatialization: various perceptually based criteria such as spatial homogeneity or spatial masking are represented as a grey shaded map superimposed to the background of a bird’s eye view interface. After selecting a given sound source, the user is thus informed how these criteria will behave if the source is being moved to any other location of the virtual sound scene.

P3-8 A New Approach for Direct Interaction with Graphical Representations of Room Impulse Responses for Use in Wave Field Synthesis Reproduction—Frank Melchior, Jan Langhammer, Fraunhofer IDMT - Ilmenau, Germany; Diemer de Vries, Technical University of Delft - Delft, The NetherlandsRoom simulation based on convolution is state-of-the-art in modern audio processing environments. Most of the systems currently available provide only a few controllers to modify the underlying room impulse responses. The sound designer can manipulate one set of numeric parameters even in spatial reproduction systems. This paper describes a new approach for the interactive control of room impulse responses based on visualization and parameterization. The new principle is originally developed for the use in wave field synthesis systems and based on augmented reality user interfaces. An adaptation to conventional user interfaces and other spatial sound reproduction systems is possible. The modification of the room impulse responses is performed by direct interaction with 3-D graphical representations of multitrace room impulse responses.

P3-9 Direct Audio Coding: Filterbank and STFT-Based Design—Ville Pulkki, Helsinki University of Technology - Espoo, Finland; Christof Faller, EPFL - Lausanne, SwitzerlandDirectional audio coding (DirAC) is a method for spatial sound representation, applicable to arbitrary audio reproduction methods. In the analysis part, properties of the sound field in time and frequency in a single point are measured and transmitted as side information together with one or more audio waveforms. In the synthesis part, the properties of the sound field are reproduced using separate techniques for point-like virtual sources and diffuse sound. Different implementations of DirAC are described and differences between them are discussed. A modification of DirAC is presented, which provides a link to Binaural Cue Coding and parametric multichannel audio coding in general (e.g., MPEG Surround).